Error while creating a registered connection


  • Good day!

    we are using a Quectel chip to connect to the NB-IoT network. Now we are making first attempts on the connection. We proceeded step by step according to the “NarrowBand IoT Quick Start Guide” and came till here:
    #Now data is sent through the open socket to the gateway server with IP

    #172.25.102.151 on port 1883. 29 bytes of data are sent. The sent data represents

    #a MQTT-SN CONNECT query to the Cloud of Things gateway server. This should

    #be acknowledged by the server by sending a CONNACK (hex: 030500). The data

    #should be sent as usual in the hex string format. Exchanging <IMSI> and <PW> by

    #one of your valid IMSI/Password combinations, formatted in hex strings, should

    #result in the described behavior. at+nsost=0,”172.25.102.151”,1883,29,”1D0404010384<IMSI><PW>”

    0,29

    OK

    Unfortunatelly it was not possible to connect to the server via command: at+nsost=0,”172.25.102.151”,1883,29,”1D0404010384<IMSI><PW>” It works neither with hexadecimal converted strings, nor the IMSI and PW as ASCII. We don’t know what should stay istead of <IMSI><PW> What should be entered in there? In response, we always got only one error and we tried pretty much all variants, whether converted, normal, with <> or without etc …

    Can you explain in simple words how to build the command set that works?

    Currently I have the feeling that in principle a connection can be established otherwise the previous registration steps would have already failed and thus we have network coverage in Tettnang - which is very good. Unfortunately, it has not been possible to register yet.

    I’m looking forward to a quick help 🙂



  • Hello,

    Your log file makes it clear that you are not connected to the cloud of things. As I mentioned in my first post, you need to get a CONNACK packet after sending the CONNECT command. The CONNACK packet consists of 3 bytes (0x030500 - see MQTT-SN specification!). However, after sending the CONNECT packet, you will receive a packet with a length of 2 bytes in your log. This can be recognized by the answer
    +NSONMI:0,2
    However, you do not have this answer in the log as described in the Quick Start Guide with the command

    AT+NSORF=0,2
    Only then you know what the server has answered. However, I suspect that this is a DISCONNECT package (0x0218). This indicates a mistake. In such a case please check again whether you are using the correct IMSI / password combination. If this is the case I would ask you to contact me by e-mail (see profile), so that we can investigate the problem.


 

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